Catheter with stacked spine electrode assembly

ABSTRACT

A catheter comprising an elongated catheter body, an electrode array distal of the catheter body, the array having a mounting member and at least first and second spine supports. Each spine support includes a base having a planar configuration, and a plurality of spines extending from the base, wherein the first base extends in a first plane and the second base extends in a second plane different from the first plane in the mounting member.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a Continuation under 35 U.S.C. § 120 of U.S.patent application Ser. No. 17/344,765, filed Jun. 10, 2021, which is aContinuation under 35 U.S.C. § 120 of U.S. patent application Ser. No.16/684,220, filed Nov. 14, 2019, now U.S. Pat. No. 11,039,772, which isa Continuation under 35 U.S.C. § 120 of U.S. patent application Ser. No.15/960,163, filed Apr. 23, 2018, now U.S. Pat. No. 10,506,938, which isa Continuation under 35 U.S.C. § 120 of U.S. patent application Ser. No.14/754,566, filed Jun. 29, 2015, now U.S. Pat. No. 9,949,656. The entirecontents of these applications are incorporated by reference herein intheir entirety.

FIELD OF INVENTION

This invention relates to catheters, in particular, intravascularcatheters for tissue diagnostics and ablation.

BACKGROUND

Cardiac arrhythmia, such as atrial fibrillation, occurs when regions ofcardiac tissue abnormally conduct electric signals to adjacent tissue,thereby disrupting the normal cardiac cycle and causing asynchronousrhythm. Important sources of undesired signals are located in the tissueregion, for example, one of the atria or one of the ventricles.Regardless of the sources, unwanted signals are conducted elsewherethrough heart tissue where they can initiate or continue arrhythmia.

Procedures for treating arrhythmia include surgically disrupting theorigin of the signals causing the arrhythmia, as well as disrupting theconducting pathway for such signals. More recently, it has been foundthat by mapping the electrical properties of the endocardium and theheart volume, and selectively ablating cardiac tissue by application ofenergy, it is possible to cease or modify the propagation of unwantedelectrical signals from one portion of the heart to another. Theablation process destroys the unwanted electrical pathways by formationof non-conducting lesions.

In this two-step procedure—mapping followed by ablation—electricalactivity at points in the heart is typically sensed and measured byadvancing a catheter containing one or more electrical sensors into theheart, and acquiring data at a multiplicity of points. These data arethen utilized to select the target areas at which ablation is to beperformed.

For greater mapping resolution, it is desirable for a mapping catheterto provide very high density signal maps through the use of a multitudeof electrodes sensing electrical activity within a small area, forexample, about a square centimeter. For mapping within an atria or aventricle (for example, an apex of a ventricle), it is desirable for acatheter to collect larger amounts of data signals within shorter timespans. It is also desirable for such a catheter to be adaptable todifferent tissue surfaces, for example, flat, curved, irregular ornonplanar surface tissue, yet remain in a predetermined configurationwhere electrode spatial relationships are generally maintained duringsensing and mapping. Moreover, with the need for greater electrodedensity, it is desirable for the catheter to accommodate additionalelectrode support structures in a manner that allows for more complexelectrode arrays with improved tissue contact and manufacturability.

SUMMARY OF THE INVENTION

The catheter of the present invention provides a distal electrodeassembly or array that has a more simplistic construction for improvedmanufacturability and yet is able to accommodate complex electrodearrays for greater electrode density and tissue contact. The catheterincludes an electrode array comprising a mounting member with a lumenand one or more spine supports, with each spine support including a basehaving a planar configuration, and a plurality of spines extending fromthe base, wherein each base occupies in a different plane in the lumen.

With a planar configuration, each base is advantageously positioned inthe mounting member or stem in a “stacked” configuration where each baseoccupies a different plane in the lumen of the stem. For example, the“stacked” configuration may include a “storied” (or “multi-storied”)configuration, where each occupies a different plane in the lumen of themounting stem. Depending on the volume of space available in the stemand the plurality of bases, the bases may be aligned and be separated bya space gap from adjacent bases, similar to floors of a multi-storiedbuilding wherein each floor occupies a different plane and is separatedby a space gap from adjacent floors.

In some embodiments, each spine includes a proximal portion and a distalportion, and the distal portions of the array extend in a common plane.The distal portions of the array may be linear. The distal portions maybe parallel with each other. The common plane may be parallel with atleast one of the planes occupied by the bases.

In some embodiments, each spine has a free distal end. In someembodiments, each spine has a distal end that is connected to at leastone distal end of another spine.

The present invention is also directed to catheter comprising anelongated catheter body, and an electrode array, the array comprising amounting stem and at least first and second spine supports, each spinesupport including a base having a planar configuration, and a pluralityof spines extending from the base. The array also includes anonconductive covering on each spine, and one or more electrodes carriedon the spines. The first base is fixed in a lumen of the stem at a firstplane and the second base is fixed in the lumen of the stem at a secondplane different from the first plane.

The present invention is further directed to a catheter comprising anelongated catheter body, an electrode array distal of the catheter body,the array comprising a mounting stem, and at least first and secondspine supports, each spine support including a base having a planarconfiguration, and a plurality of spines extending from the base. Thearray also includes a nonconductive covering on each spine, and one ormore electrodes carried on the spines. The first base is fixed in alumen of the stem at a first plane, the second base is fixed in thelumen of the stem at a second plane different from the first plane, andeach spine has a distal linear portion, and the distal linear portionsof the array are parallel with each other.

In some embodiments, the distal linear portions of the array areparallel with a longitudinal axis of the stem.

In some embodiments, the plurality of spines ranges between about twoand six.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view of a catheter of the present invention, inaccordance with some embodiments.

FIG. 2A is a side cross-sectional view of the catheter of FIG. 1 ,including a junction between a catheter body and a deflection section,taken along a first diameter.

FIG. 2B is a side cross-sectional view of the catheter of FIG. 1 ,including the junction of FIG. 2A, taken along a second diametergenerally perpendicular to the first diameter.

FIG. 2C is an end cross-sectional view of the deflection section ofFIGS. 2A and 2B, taken along line C-C.

FIG. 3A is a side cross-sectional view of the catheter of FIG. 1 ,including a junction between the deflection section and a distalelectrode assembly, taken along a first diameter.

FIG. 3B is a side cross-sectional view of the junction of FIG. 3A, takenalong a second diameter generally perpendicular to the first diameter.

FIG. 3C is an end cross-sectional view of the deflection section ofFIGS. 3A and 3B, taken along line C-C.

FIG. 3D is an end cross-sectional view of the junction of FIGS. 3A and3B, taken along line D-D.

FIG. 4A is a perspective view of a junction between the deflectionsection and the distal electrode assembly, with parts broken away, inaccordance with one embodiment.

FIG. 4B is an end cross-sectional view of a ring electrode mounted on aspine of FIG. 4A, taken along line B-B.

FIG. 5 is a partial perspective view of a spine support and a mountingstem, of FIG. 4A.

FIG. 6A is a detailed perspective view of the spine support and mountingstem of FIG. 5 .

FIG. 6B is an end view of the spine support and mounting stem of 6A.

FIG. 7A is a perspective view of an irrigated ring electrode mounted ona spine, in accordance with one embodiment.

FIG. 7B is a side cross-sectional view of the irrigated ring electrodeof FIG. 7A, taken along line A-A.

FIG. 7C is an end cross-sectional view of the irrigated ring electrodeof FIG. 7B, taken along line B-B.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1 , the catheter 10 comprises an elongated catheterbody 12, an intermediate deflection section 14, a distal electrodeassembly or array 15 with a plurality of spines, and a deflectioncontrol handle 16 attached to the proximal end of the catheter body 12.In accordance with a feature of the present invention, the distalelectrode array 15 includes multiple spine supports that enable thespines to be mounted to the distal end of the catheter in a spatiallyefficient manner that accommodates more complex spine geometries whileimproving electrode-to-tissue contact and manufacturability of thecatheter.

With reference to FIGS. 2A and 2B, the catheter body 12 comprises anelongated tubular construction having a single, axial or central lumen18. The catheter body 12 is flexible, i.e., bendable, but substantiallynon-compressible along its length. The catheter body 12 can be of anysuitable construction and made of any suitable material. In someembodiments, the catheter body 12 comprises an outer wall 20 made ofpolyurethane or PEBAX. The outer wall 20 comprises an imbedded braidedmesh of stainless steel or the like to increase torsional stiffness ofthe catheter body 12 so that, when the control handle 16 is rotated, theintermediate section 14 of the catheter 10 rotates in a correspondingmanner.

The outer diameter of the catheter body 12 is not critical. Likewise,the thickness of the outer wall 20 is not critical, but is thin enoughso that the central lumen 18 can accommodate a puller wire, one or morelead wires, and any other desired wires, cables or tubes. If desired,the inner surface of the outer wall 20 is lined with a stiffening tube22 to provide improved torsional stability.

As shown in FIGS. 2A, 2B and 2C, the intermediate section 14 comprises ashorter section of tubing 19 having multiple lumens, for example, fouroff-axis lumens 31, 32, 33 and 34. The first lumen 31 carries aplurality of lead wires 40S for ring electrodes 37 mounted on the array15. The second lumen 32 carries a first puller wire 24. The third lumen33 carries a cable 36 for an electromagnetic position sensor 42 and aplurality of lead wires 40D and 40P for distal and proximal ringelectrodes 38D and 38P carried on the catheter proximally of the distalelectrode array 15. The fourth lumen 34 (for example, diametricallyopposite of the second lumen 32 in the illustrated embodiment) carries asecond puller wire 26. The tubing 19 is made of a suitable non-toxicmaterial that is preferably more flexible than the catheter body 12. Onesuitable material for the tubing 19 is braided polyurethane, i.e.,polyurethane with an embedded mesh of braided stainless steel or thelike. The size of each lumen is not critical, but is sufficient to housethe lead wires, puller wires, the cable and any other components.

The useful length of the catheter, i.e., that portion that can beinserted into the body excluding the distal electrode array 15, can varyas desired. Preferably the useful length ranges from about 110 cm toabout 120 cm. The length of the intermediate section 14 is a relativelysmaller portion of the useful length, and preferably ranges from about3.5 cm to about 10 cm, more preferably from about 5 cm to about 6.5 cm.

A means for attaching the catheter body 12 to the intermediate section14 is illustrated in FIGS. 2A and 2B. The proximal end of theintermediate section 14 comprises an outer circumferential notch 27 thatreceives the inner surface of the catheter body 12. The intermediatesection 14 and catheter body 12 are attached by glue or the like.

If desired, a spacer (not shown) can be located within the catheter bodybetween the distal end of the stiffening tube (if provided) and theproximal end of the intermediate section. The spacer provides atransition in flexibility at the junction of the catheter body andintermediate section, which allows this junction to bend smoothlywithout folding or kinking. A catheter having such a spacer is describedin U.S. Pat. No. 5,964,757, the disclosure of which is incorporatedherein by reference.

As shown in FIGS. 3A and 3B, the distal electrode array 15 includes amounting member or stem 46 in the form of a short tubing mounted on adistal end of the tubing 19 of the intermediate deflection section 14.It is understood that the stem may be mounted onto the distal end of thecatheter body 12 where the catheter includes no deflection section. Thestem 46 has a central lumen 48 to house various components. Theintermediate section 14 and stem 46 are attached by glue or the like.The stem 46 may be constructed of any suitable material, includingnitinol.

As shown in FIG. 4A, the stem 46 houses various components, including,for example, the electromagnetic position sensor 42, and a distal anchorfor the puller wires 24 and 26. In the disclosed embodiment, the distalanchor includes one or more washers, for example, a distal washer 50Dand a proximal washer 50P, each of which has a plurality of matchingaxial through-holes that allow passage of components between thedeflection section 14 and the stem 46 while maintaining axial alignmentof these components relative to the longitudinal axis 95 of the catheter10. As shown in FIG. 3D, the through-holes include holes 54 and 56 thatare axially aligned with the second and fourth lumens 32 and 34 of thetubing 19, respectively, to receive a distal end of puller wires 24 and26, respectively. It is understood that the puller wires 24 and 26 mayactually form a single tensile member with a distal U-bend section thatpasses through the holes 54 and 56. With tension on the washers 50D and50P exerted by the U-bend section of the puller wires 24 and 26, thewashers firmly and fixedly abut against the distal end of the tubing 19of the deflection section 14 to distally anchor the U-bend section.

As shown in FIG. 3D, each washer also includes through-hole 58 which isaxially aligned with the first lumen 31 and allows passage of the leadwires 40S from the deflection section 14 and into the lumen 48 of thestem 46. Each washer further includes through-hole 57 which is axiallyaligned with the third lumen 33 and allows passage of the sensor cable36 from the deflection section 14 into lumen 48 of the stem 46 where theelectromagnetic position sensor 42 is housed. The lead wire 40D alsopasses through the hole 57 to enter the lumen 48 for attachment to thedistal ring electrode 38D carried on the outer surface of the stem 46via an opening (not shown) formed in the side wall of the stem 46through which a distal end of the lead wire 40D is welded or otherwiseattached to the distal ring electrode 38D, as known in the art. Carriedon the outer surface of the tubing 19 near the distal end of theintermediate deflection section 14, a proximal ring electrode 38P isconnected to lead wire 40P via an opening 87 (FIG. 3B) formed in theside wall of the tubing 19 that provides communication between the thirdlumen 33 and outside of the tubing 19. The distal end of the lead wireis welded or otherwise attached to the proximal ring electrode 38P asknown in the art.

With reference to FIGS. 4A, 5, 6A and 6B, multiple spine supports 21 areanchored in the lumen 48 near the distal end of the stem 46, with eachsupport 21 having a base 23 and a plurality of spines 25 extending froma distal edge of the base 23. Each spine 25 has at least a proximalportion 25P and a distal portion 25D. The spines 25 may extend likefingers with free distal ends (see solid lines in FIG. 1 ), or thespines may have their distal ends connected forming closed loops (seebroken lines in FIG. 1 ). With a planar configuration, each base 23 isadvantageously positioned in the stem 46 in a “stacked” configurationwhere each base 23 occupies a different plane in the stem 46. Forexample, the “stacked” configuration may include a “storied” or“multi-storied” configuration, where each base 23 is aligned with eachother, occupying a different plane in the stem 46. Depending on thevolume of space available in the stem and the plurality of bases, thebases may be separated by a space gap from adjacent bases 23, similar tofloors of a multi-storied building wherein each floor occupies adifferent plane and is separated by a space gap from adjacent floors. Itis understood that the stem 46 may have any appropriate or desiredcross-sectional shape, including, for example, circular, oval,rectangular and polygonal.

In the illustrated embodiment, the array 15 has a first spine support 21a and a second spine support 21 b, where the bases 23 a and 23 b occupyor extend in planes Pa and Pb, respectively, and are separated by adistance d. As such, the spines 25 a and 25 b extending from the bases23 a and 23 b have the freedom to extend in multiple differentdirections while the bases 23 a and 23 b occupy minimal space in thestem 46. Construction and manufacturability of the array 15 are alsosimplified by the stacking arrangement of the bases.

More complex array geometries may include the distal spine portions 25Daand 25Db all extending within a common plane Pc, despite theirrespective bases 23 a and 23 b being in different planes Pa and Pbwithin the stem 46 (see FIG. 5 ). For example, the planes Pa and Pb maybe parallel or nonparallel to each other, as desired or appropriate, andthe plane Pc may be co-planar with the plane Pa or with the plane Pb, orit may define a different plane from planes Pa and Pb (parallel ornonparallel with plane Pc).

It is understood, especially from FIGS. 6A and 6B, that the stem 46 canaccommodate additional bases in its lumen 48 between the bases 23 a and23 b, above the base 23 a and/or below the base 23 b to provide thearray 15 with additional spines, as desired or appropriate. The bases 23securely anchor the spines 15 within the stem 46, and greatly simplifythe assembly and mounting of the array 15 onto the distal end of thecatheter, whether the stem is mounted on a distal end of the deflectionsection 14, or of the catheter body 12 where the catheter has nodeflection section 14.

As best shown in FIG. 6B, the proximal spine portions 25Pa may extendfrom its base 23 a at different locations from the locations at whichthe proximal spine portions 25Pb may extend from its base 23 b, so thatthe proximal spine portions 25Pa are laterally offset from the proximalspine portions 25Pb, even though the bases 23 a and 23 b are aligned.

In the illustrated embodiments, both of the proximal spine portions 25Pand the distal spine portions are linear 25D, however, the proximalspine portions 25P diverge from the longitudinal axis of the stem 46,whereas the distal spine portions 25D are parallel with the longitudinalaxis of the stem 46.

Each spine 25 has a nonconductive tubing or covering 64 along itslength, as shown in FIG. 4A. On each spine 25, one or more ringelectrodes 37 are mounted over the covering 64. Proximal of the array15, the lead wires 40S for the ring electrodes 37 extend through aprotective polytube 68. The lead wires 40S diverge near the distal endof the polytube 68, and extend toward their respective spine 25, intolumen 65 of the respective nonconductive covering 64. As shown in FIG.4B, each lead wire 40S is connected to its respective ring electrode 37via a respective opening 69 formed in the side wall of the covering 64through which a distal end of the lead wire reaches outside of thecovering 64 and is welded or otherwise attached to its ring electrode37.

In other embodiments, irrigated ring electrodes 371 are carried on thespines 25, as shown in FIGS. 7A, 7B and 7C. Each spine 25 is covered bya respective multi-lumened tubing 80 having, for example, a first lumen81 through which the spine extends, a second lumen 82 for lead wires40S, and a third lumen 83 for passing irrigation fluid via a passage 88formed in the sidewall of the tubing 80 to annular space gap G betweenouter wall of the tubing 80 and side wall of the ring electrode 371which are formed with fluid ports 85.

In some embodiments, the ring electrodes (irrigated or nonirrigated) arecarried on the distal spine portions 25D. The plurality of ringelectrodes on each spine may range between about 4 and 11, preferablyabout 6 and 9, and more preferably about 8. Depending on the pluralityof spines, the distal electrode array 15 may carry a plurality ofelectrodes ranging between about 20 and 44, preferably between about 28and 36 electrodes, and more preferably about 32 electrodes. In someembodiments, the electrode density is about 15 electrodes per squarecentimeter and dimensions of about 12 mm×18 mm.

In some embodiments, the spine supports 23 and the stem 46 are made of amaterial having shape-memory, i.e., that can be temporarily straightenedor bent out of its original shape upon exertion of a force and iscapable of substantially returning to its original shape in the absenceor removal of the force. One suitable material for the support member isa nickel/titanium alloy. Such alloys typically comprise about 55% nickeland 45% titanium, but may comprise from about 54% to about 57% nickelwith the balance being titanium. A nickel/titanium alloy is nitinol,which has excellent shape memory, together with ductility, strength,corrosion resistance, electrical resistivity and temperature stability.The spine supports may be formed from a sheet material which is, forexample, die cut or laser cut into the configuration of the base and thespines. Side edges of the bases 23 may be affixed to inner surface ofthe stem 46 by any suitable manner, e.g., laser welding, adhesives, orthe like. The non-conductive coverings 64 or the tubings 80 surroundingthe spines 25 can be made of any suitable material, and is preferablymade of a biocompatible plastic such as polyurethane or PEBAX.

At the junction of distal electrode array 15 and the stem 46, thenon-conductive covering 64 or the multi-lumened tubing 80 of each spine25 may be attached and sealed at its proximal end to the stem 46 by thepolyurethane or the like.

The proximal ends of the lead wires 40S, 40D and 40P for the spine loopring electrodes 37, and for the distal and proximal ring electrodes 38Dand 38P proximal of the array 15, respectively, are electricallyconnected to a suitable connector (not shown) in the distal end of thecontrol handle 16, which is connected to a source of ablation energy,e.g., RF energy, as is known in the art. The lead wires 40S, 40D and 40Pextend through the central lumen 18 of the catheter body 12 (FIG. 2B).The lead wires 40S extend through the first lumen 31 of the tubing 19 ofthe intermediate section 14, and the lead wires 40D and 40P extendthrough the third lumen 33 of the tubing 19 (FIGS. 2C and 3C). Passingthrough the holes 58 in the washers 50D and 50P, the lead wires 40Sextend through the polytube 68 which protects them from being damaged bythe hole 58 (FIG. 3D).

In the depicted embodiment, the lead wires 40S extending through thecentral lumen 18 of the catheter body 12 and the first lumen 31 in thedeflection section 14 may be enclosed within a protective sheath 94 toprevent contact with other components in the catheter. The protectivesheath can be made of any suitable material, preferably polyimide. Aswould be recognized by one skilled in the art, the protective sheath canbe eliminated if desired.

The ring electrodes 37, 371 and 38D and 38P are made of any suitablesolid conductive material, such as platinum or gold, preferably acombination of platinum and iridium, and mounted onto the non-conductivecover 64 and the stem 46 with glue or the like. Alternatively, the ringelectrodes can be formed by coating the non-conductive cover 64 and stem46 with an electrically conducting material, like platinum, gold and/oriridium. The coating can be applied using sputtering, ion beamdeposition or an equivalent technique.

In some embodiments, each ring electrode carried on the spines 25 isrelatively short, having a length ranging from about 0.4 mm to about0.75 mm. Moreover, the electrodes may be arranged in pairs, where twoelectrodes of a pair are spaced more closely to each other than they areto other pairs of electrodes. The closely-spaced electrode pairs allowfor more accurate detection of near field pulmonary vein potentialversus far field atrial signals, which is very useful when trying totreat atrial fibrillation. Specifically, the near field pulmonary veinpotentials are very small signals whereas the atria, located very closeto the pulmonary vein, provides much larger signals. Accordingly, evenwhen the mapping array is placed in the region of a pulmonary vein, itcan be difficult for the physician to determine whether the signal is asmall, close potential (from the pulmonary vein) or a larger, fartherpotential (from the atria). Closely-spaced bipole electrodes permit thephysician to more accurately determine whether he is looking at a closesignal or a far signal. Accordingly, by having closely-spacedelectrodes, one is able to target exactly the locations of myocardialtissue that have pulmonary vein potentials and therefore allows theclinician to deliver therapy to the specific tissue. Moreover, theclosely-spaced electrodes allow the physician to determine the exactanatomical location of the ostium/ostia by the electrical signal.

In some embodiments, a proximal electromagnetic position sensor 42P ishoused in the lumen 48 of the stem 46 (FIG. 4A). A sensor cable 36Pextends from a proximal end of the position sensor 42P, and through thehole 57 of the washers 50 (FIG. 3D), the third lumen 33 of the tubing 19of the deflection section 14 (FIG. 2C), and the central lumen 18 of thecatheter body 12 (FIG. 2B). The cable 36P is attached to a PC board inthe control handle 16, as known in the art. In some embodiments, one ormore distal electromagnetic position sensors may be housed in the array,for example, in one or more distal portions of the array. Sensorcable(s) 36D may extend through the lumen 65 of spine covering 64 (FIG.4B) or a fourth lumen 84 of the tubing 80 (FIG. 7C).

As shown in FIGS. 2A and 2C, the puller wires 24 and 26 (whether as twoseparate tensile members or parts of a single tensile member) areprovided for bi-directional deflection of the intermediate section 14.The puller wires 24 and 26 are actuated by mechanisms in the controlhandle 16 that are responsive to a thumb control knob or a deflectioncontrol knob 11. Suitable control handles are disclosed in U.S. Pat.Nos. 6,123,699; 6,171,277; 6,183,435; 6,183,463; 6,198,974; 6,210,407and 6,267,746, the entire disclosures of which are incorporated hereinby reference.

The puller wires 24 and 26 extend through the central lumen 18 of thecatheter body 12 (FIG. 2A) and through the second and fourth lumens 32and 34, respectively, of the tubing 19 of the deflection section 14(FIG. 2C). As shown in FIGS. 3A and 3C, they extend through holes 54 and56, respectively of the washers 50. Where the puller wires are part of asingle tensile member, the single tensile member has a U-bend 24/26U(FIG. 3A) at the distal face of the distal washer 50D which anchors thedistal ends of the puller wires. In that regard, the U-bend extendsthrough a short protective tubing 70 to protect the puller wires fromthe holes 54 and 56. Alternatively, where the puller wires are separatetensile members, their distal ends may be anchored via T-bars, as knownin the art and described in, for example, U.S. Pat. No. 8,603,069, theentire content of which is incorporated herein by reference. In anycase, the puller wires 24 and 26 are made of any suitable metal, such asstainless steel or Nitinol, and each is preferably coated with TEFLON orthe like. The coating imparts lubricity to the puller wires. The pullerwires preferably have a diameter ranging from about 0.006 to about 0.010inch.

A compression coil 66 is situated within the central lumen 18 of thecatheter body 12 in surrounding relation to each puller wire 24, asshown in FIG. 2B. Each compression coil 66 extends from the proximal endof the catheter body 12 to the proximal end of the intermediate section14. The compression coils 66 are made of any suitable metal, preferablystainless steel. Each compression coil 66 is tightly wound on itself toprovide flexibility, i.e., bending, but to resist compression. The innerdiameter of the compression coil 66 is preferably slightly larger thanthe diameter of its puller wire. The Teflon coating on each puller wireallows it to slide freely within its compression coil.

The compression coil 66 is anchored at its proximal end to the outerwall 20 of the catheter body 12 by a proximal glue joint (not shown) andat its distal end to the intermediate section 14 by a distal glue joint92. Both glue joints may comprise polyurethane glue or the like. Theglue may be applied by means of a syringe or the like through a holemade the sidewalls of the catheter body 12 and the tubing 19. Such ahole may be formed, for example, by a needle or the like that puncturesthe sidewalls which are heated sufficiently to form a permanent hole.The glue is then introduced through the hole to the outer surface of thecompression coil 66 and wicks around the outer circumference to form aglue joint about the entire circumference of the compression coil.

Within the second and fourth lumens 32 and 34 of the intermediatedeflection section 14, each puller wire 24 and 26 extends through aplastic, preferably Teflon, puller wire sheath 39 (FIGS. 2A and 2C),which prevents the puller wires from cutting into the wall of the tubing19 of the deflection section 14 when the deflection section 14 isdeflected.

In some embodiments, the ring electrodes 38D and 38P proximal of thearray 15 serve as reference electrodes for visualization of the catheteron a 3-D mapping system, such as CARTO® 3 SYSTEM available from BiosenseWebster, Inc., which automatically locates the EM sensor 42, processesreference location values from electrodes 38D and 38P, which are at aconstant location from the EM sensor(s) and determines the location ofthe electrodes 37 and 371 and visualizes the remainder of the electrodearray 15.

The preceding description has been presented with reference to presentlypreferred embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention. As understood by one of ordinary skill in the art, thedrawings are not necessarily to scale. Also, different features ofdifferent embodiments may be combined as needed or appropriate.Moreover, the catheters described herein may be configured to applyvarious energy forms, including microwave, laser, RF and/or cryogens.Accordingly, the foregoing description should not be read as pertainingonly to the precise structures described and illustrated in theaccompanying drawings, but rather should be read consistent with and assupport to the following claims which are to have their fullest and fairscope.

What is claimed is:
 1. A catheter comprising: an elongated catheterbody; and an electrode array distal of the catheter body, the arraycomprising a first spine support including a first base and a firstplurality of spines having first distal spine portions and firstproximal spine portions extending from the first base, and a secondspine support including a second base and a second plurality of spineshaving second distal spine portions and second proximal spine portionsextending from the second base and laterally offset from the firstproximal spine portions, a first plurality of ring electrodes disposedon the first distal spine portion, the first plurality of ringelectrodes comprising between about four and about eleven ringelectrodes, and a second plurality of ring electrodes disposed on thesecond distal spine portion.
 2. The catheter of claim 1, in which thefirst plurality of ring electrodes comprises between six and nine ringelectrodes.
 3. The catheter of claim 2, in which the first plurality ofring electrodes comprises eight ring electrodes.
 4. The catheter ofclaim 1, in which the second plurality of ring electrodes comprisesbetween about four and about eleven ring electrodes.
 5. The catheter ofclaim 4, in which second plurality of ring electrodes comprises betweensix and nine ring electrodes.
 6. The catheter of claim 5, in whichsecond plurality of ring electrodes comprises eight ring electrodes. 7.The catheter of claim 1, in which the first plurality of ring electrodescomprise irrigated ring electrodes.
 8. The catheter of claim 7, in whichthe second plurality of ring electrodes comprise irrigated ringelectrodes.
 9. The catheter of claim 1, in which the first plurality ofring electrodes and second plurality of ring electrodes are provided ashaving an electrode density of about fifteen ring electrodes per squarecentimeter.
 10. The catheter of claim 1, in which a length of each ringelectrode of the first plurality of ring electrodes and the secondplurality of ring electrodes ranges from about 0.4 millimeters to about0.75 millimeters.
 11. The catheter of claim 1, in which a first ringelectrode of the first plurality of ring electrodes and a second ringelectrode of the first plurality of ring electrodes are positionedcloser to each other than to any other of the ring electrodes of thefirst plurality of ring electrodes.